The ability of our auditory systems to recognize target sounds in a mixture of other sounds is fundamental to normal healthy function and communication. For example, during the course of a normal day we must communicate with a conversation partner in the presence of other sounds, e.g., other people talking, music, sound of cars etc. Like humans, many animals are capable of listening to a single sound source in a mixture of sources. Thus, neural circuits for solving the CPP also likely exist in animals. This proposal, will investigate how the auditory cortex contributes to solving this problem by unraveling cortical circuitry that underlies the processing of complex sound mixtures, using powerful experimental tools available in mice. By providing new insights into cortical mechanisms that help solve this problem in the normal brain, this proposal may impact the development of novel therapeutic strategies for the hearing impaired, who have great difficulty solving this problem, and improve hearing assistive devices, e.g., hearing aids and cochlear implants.